Ray Effects and False Scattering in Improved Discrete Ordinates Method

The improved discrete ordinates method (IDOM) developed in our previous paper is extended to solve radiative transfer in three-dimensional radiative systems with anisotropic scattering medium. In IDOM, radiative intensities in a large number of new discrete directions are calculated by direct integration of the conventional discrete ordinates method (DOM) results, and radiative heat flux is obtained by integrating radiative intensities in these new discrete directions. Ray effects and false scattering, which tend to compensate each other, are investigated together in IDOM. Results show that IDOM can mitigate both of them effectively with high computation efficiency. Finally, the effect of scattering phase function on radiative transfer is studied. Results of radiative heat flux at boundaries containing media with different scattering phase functions are compared and analyzed. This paper indicates that the IDOM can overcome the shortages of the conventional DOM well while inheriting its advantages such as high computation efficiency and easy implementation.

The Application of Calcium Carbonate CaCO3 and Titania TiO2 for Color Homogeneity and Luminous Flux Enhancement in PC-LEDs

This article studies the development method of pc-LED, a phosphor-converted lighting emitting diode, with scattering enhancement particles (SEPs) at 7000 K correlated color temperature. The pc-LED is an advanced lighting solution that has been applied in many different categories; nonetheless, to keep up with the demands of modern lighting, the pc-LEDs need to enhance the color homogeneity and luminous flux. The detailed experiments on the two SEPs used in the articles are also presented. The experiments include combining each of these SEPs with a yellow phosphor Y3Al5O12:Ce3+ to test their properties and influences on the lighting of pc-LEDs. The scattering coefficients, the anisotropic scattering, the reduced scattering, and the scattering amplitudes at 450 nm and 550 nm are the subjects of SEPs study. The LightTools program is used to create the simulation of pc-LED, the results of the optical simulation will then be verified with the Mie-scattering theory. The findings of the research conclude that TiO2 particles are the best for the growth of color homogeneity while CaCO3 particles are effective in limiting the color deviation in correlated color temperature. Even though the SEPs benefit the lighting performance, their concentration must be managed to be under an acceptable amount to ensure desired results and avoid unwanted damages.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.